The subject matter disclosed herein relates to an X-ray CT (Computerized Tomography) apparatus, and particularly to an X-ray CT apparatus capable of reducing the amount of computation when image reconstruction is carried out using projection data acquired when a cradle is moved under acceleration/deceleration upon a helical scan.
When the acquisition of projection data used in image reconstruction is performed by a helical scan in an X-ray CT apparatus, an X-ray tube and an X-ray detector comprised of a plurality of X-ray detecting elements are rotated about a subject, and a cradle with the subject placed thereon is moved linearly.
There is also a ease where the acquisition of projection data is carried out only during a period in which the travel velocity of the cradle is maintained constant, of a linear travel distance of the cradle. There is, however, also a case where as described in, for example, Japanese Unexamined Patent Publication No. 2005-40582, projection data are acquired even when the cradle is being accelerated/decelerated. Carrying out the acquisition of projection data using even the travel distance for acceleration/deceleration, of the linear travel distance of the cradle in this way makes it possible to acquire the projection data at a short travel distance and perform the acquisition of the projection data in a short period of time.